Phosphorylation state of the GLUT4 isoform of the glucose transporter in subfractions of the rat adipose cell: effects of insulin, adenosine, and isoproterenol.
Phosphorylation state of the GLUT4 isoform of the glucose transporter in subfractions of the rat adipose cell: effects of insulin, adenosine, and isoproterenol.
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大鼠脂肪细胞亚组分中葡萄糖转运蛋白 GLUT4 亚型的磷酸化状态：胰岛素、腺苷和异丙肾上腺素的作用。
DOI：
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发表时间：
1991
影响因子：
11.1
通讯作者：
I. Simpson
中科院分区：
文献类型：
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作者：
H. Nishimura;J. Saltis;A. D. Habberfield;N. Garty;A. Greenberg;S. Cushman;C. Londos;I. Simpson
在大鼠脂肪细胞中研究了胰岛素、腺苷和异丙肾上腺素对GLUT 4葡萄糖转运蛋白亚型的活性、亚细胞分布和磷酸化状态的急性效应，这些研究在严格控制的条件下进行，以监测cAMP依赖性蛋白激酶（A-激酶）活性的变化。与GLUT 1相反，即使当细胞暴露于任何上述试剂时，GLUT 1也未显示出磷酸化，当A-激酶的活性被抑制时，GLUT 4被部分磷酸化（0.1-0.2 mol/mol），并且响应于胰岛素保持不变。在腺苷受体激动剂不存在但不存在的情况下，异丙肾上腺素引起胰岛素刺激的葡萄糖转运活性的64%抑制。然而，在存在或不存在激动剂的情况下，通过检查主要脂肪细胞A-激酶底物周脂蛋白的磷酸化来评估A-激酶被激活。类似地，在任一条件下，GLUT 4的磷酸化在细胞内膜中增强1.4倍，但在质膜中未观察到显著变化。在没有腺苷受体激动剂的情况下，异丙肾上腺素对胰岛素诱导的GLUT 4易位产生了小的（14%）但显著的抑制作用，但对GLUT 1易位没有影响。因此，GLUT 4的磷酸化状态和/或亚细胞分布的变化不能解释由异丙肾上腺素诱导的胰岛素刺激的葡萄糖活性的抑制。
The acute effects of insulin, adenosine, and isoproterenol on the activity, subcellular distribution, and phosphorylation state of the GLUT4 glucose transporter isoform were investigated in rat adipocytes under conditions carefully controlled to monitor changes in cAMP-dependent protein kinase (A-kinase) activity. In contrast to GLUT1, which has not been shown to be phosphorylated even when cells are exposed to any of the above agents, GLUT4 was partially phosphorylated (0.1-0.2 mol/mol) when the activity of the A-kinase was suppressed, and remained unchanged in response to insulin. Isoproterenol elicited a 64% inhibition of insulin-stimulated glucose transport activity in the absence, but not the presence, of adenosine receptor agonists. However, in either the presence or the absence of agonists, A-kinase was activated as assessed by examining the phosphorylation of the major adipocyte A-kinase substrate, perilipin. Similarly, under either condition, phosphorylation of GLUT4 was enhanced 1.4-fold in the intracellular membranes, but no significant change was observed in the plasma membrane. In the absence of adenosine receptor agonists, isoproterenol exerted a small (14%) but significant inhibition of the insulin-induced translocation of GLUT4 but had no effect on the translocation of GLUT1. Thus, changes in the phosphorylation state and/or subcellular distribution of GLUT4 cannot account for the inhibition of insulin-stimulated glucose activity induced by isoproterenol.